Why do some quartz watches need the battery changing more frequently than others?

Most quartz watches are powered by a battery that powers an integrated circuit. Imagine the battery is a heart and the circuit is a human body. When the body is standing still it can be said to be doing nothing, but blood still flows from the heart around the circuit. Assuming the body has a finite energy resource it can maintain this static pose until power runs out. Now if you ask that body to physically push something the energy will deplete faster, the strain on the heart will increase, and the body’s lifespan will decrease. That’s the problem faced by the battery when you ask it to move the wheels that drive the hands and thus tell the time.

When allowing power to flow around the circuit the battery is barely flexing its muscles. The battery is just doing what it would do naturally and allowing power to flow all around it. The load, or drain, on the battery increases with the introduction of mechanical friction. As soon as the wheels come into play, powered of course by the bipolar motor, the friction of driving the train asks an awful lot of the power source.

In a Quartz Watch that has a seconds hand, an impulse is needed every second. However, for watches with no seconds hand, such a load can be reduced. It is not necessary for the motor to convert electric impulse into mechanical movement every single second, and so the impulse is ‘chopped’ into larger chunks, pulsing maybe once every 20, 30 or even 60 seconds in order to reduce the strain on the battery.

It is common for more power to be released during the date change phase of a quartz watch as it takes slightly more energy to power the movement during this period. This whole process is controlled by the Integrated Circuit (the IC), which reacts to the feedback it receives from the movement and distributes power accordingly, releasing extra juice when the movement needs a bit of a push.

For this reason, a digital watch has the lowest consumption and can get the most out of an identical battery asked to power an analogue quartz. Some analogue quartz watches are incredibly good at maximising battery life by reducing the number and weight of hands and by doing without a date function. A standard Swatch Skin watch is a good example of a lightweight, low-load quartz that will go for years without needing a battery change.

If your quartz is burning through batteries at an unusual rate this is probably due to excessive friction, which could be caused by dirt jamming up the wheels, a damaged tooth or old lubrication that needs replacing. It is a common misconception that the only thing that can go wrong with a quartz watch is the battery, although if there is a problem with the movement itself, it is more likely a watchmaker would exchange rather than fix it due to the cheapness of this revolutionary technology.

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